java 向图像添加动作侦听器

adding action listener to an image

提问by user650679

I insert an image to a JPanel. I write this code.

我将图像插入到JPanel. 我写了这段代码。

public void paint(Graphics g)
{

    img1=getToolkit().getImage("/Users/Boaz/Desktop/Piece.png");
    g.drawImage(img1, 200, 200,null);

}

I want to add an action listener to that picture, but it does not have an addActionListener()method. How can I do that without putting the image in a button or label?

我想为该图片添加一个动作侦听器，但它没有addActionListener()方法。如果不将图像放在按钮或标签中，我该怎么做？

回答by coobird

There are a few options.

有几个选项。

Use a MouseListenerdirectly in the JPanel

使用MouseListener在直接JPanel

A simple but dirty way would be to add an MouseListenerdirectly to the JPanelin which you overrode the paintComponentmethod, and implement a mouseClickedmethod which checks if the region where the image exists has been clicked.

一个简单但肮脏的方法是MouseListener直接添加一个JPanel你覆盖该paintComponent方法的方法，并实现一个mouseClicked方法来检查图像所在的区域是否已被点击。

An example would be something along the line of:

一个例子是：

class ImageShowingPanel extends JPanel {

  // The image to display
  private Image img;

  // The MouseListener that handles the click, etc.
  private MouseListener listener = new MouseAdapter() {
    public void mouseClicked(MouseEvent e) {
      // Do what should be done when the image is clicked.
      // You'll need to implement some checks to see that the region where
      // the click occurred is within the bounds of the `img`
    }
  }

  // Instantiate the panel and perform initialization
  ImageShowingPanel() {
    addMouseListener(listener);
    img = ... // Load the image.
  }

  public void paintComponent(Graphics g) {
    g.drawImage(img, 0, 0, null);
  }
}

Note: An ActionListenercan't be added to a JPanel, as a JPanelitself does not lend itself to create what is considered to be "actions".

注意： AnActionListener不能添加到 a 中JPanel，因为 aJPanel本身不适合创建被认为是“动作”的东西。

Create a JComponentto display the image, and add a MouseListener

创建一个JComponent显示图像，并添加一个MouseListener

A better way would be to make a new subclass of JComponentwhose sole purpose is to display the image. The JComponentshould size itself to the size of the image, so that a click to any part of the JComponentcould be considered a click on the image. Again, create a MouseListenerin the JComponentin order to capture the click.

更好的方法是创建一个新的子类，JComponent其唯一目的是显示图像。本JComponent应大小本身对图片的大小，使一点击的任何部分JComponent可以考虑在图像上点击。再次，建立MouseListener在JComponent以捕获点击。

class ImageShowingComponent extends JComponent {

  // The image to display
  private Image img;

  // The MouseListener that handles the click, etc.
  private MouseListener listener = new MouseAdapter() {
    public void mouseClicked(MouseEvent e) {
      // Do what should be done when the image is clicked.
    }
  }

  // Instantiate the panel and perform initialization
  ImageShowingComponent() {
    addMouseListener(listener);
    img = ... // Load the image.
  }

  public void paintComponent(Graphics g) {
    g.drawImage(img, 0, 0, null);
  }

  // This method override will tell the LayoutManager how large this component
  // should be. We'll want to make this component the same size as the `img`.
  public Dimension getPreferredSize() {
    return new Dimension(img.getWidth(), img.getHeight());
  }
}

回答by handuel

The easiest way is to put the image into a JLabel. When you use the program, it appears to just be the image, you can't tell its in a JLabel. Then just add a MouseListener to the JLabel.

最简单的方法是将图像放入 JLabel 中。当您使用该程序时，它似乎只是图像，您无法在 JLabel 中分辨它。然后只需向 JLabel 添加一个 MouseListener 即可。